Expander-integrated compressor and refrigeration cycle apparatus using the same

ABSTRACT

An expander-integrated compressor ( 100 A) has a compression mechanism ( 2 ), an expansion mechanism ( 3 ), a shaft ( 5 ), an oil pump ( 6 ), and an oil supply amount regulating mechanism ( 30 ). The compression mechanism ( 2 ) and the expansion mechanism ( 3 ) are coupled to each other by the shaft ( 5 ) so that mechanical power can be transmitted. The compression mechanism ( 2 ) and the expansion mechanism ( 3 ) are arrayed vertically in the closed casing ( 1 ). The oil pump ( 6 ) is provided at a lower portion of the shaft ( 5 ). An oil supply passage ( 29 ) is formed in the shaft ( 5 ) so as to extend in the axis direction. The oil supply amount regulating mechanism  30  controls the amount of the oil to be supplied by the oil pump ( 6 ) to the expansion mechanism ( 3 ).

TECHNICAL FIELD

The present invention relates to an expander-integrated compressor and arefrigeration cycle apparatus using the same.

BACKGROUND ART

Recently, as natural resource issues and global warming issues havebecome ever more serious, much research and development efforts havebeen invested in reducing energy consumption of refrigeration cycleapparatuses, which are used for water heaters and air conditioners. Forexample, conventional refrigeration cycle apparatuses have a mechanismof expanding the refrigerant using an expansion valve, but there is anattempt to employ a positive displacement expander in place of theexpansion valve in order to recover the energy of expansion of therefrigerant and utilize it as auxiliary power for the compressor. By therecovery and utilization of the expansion energy of the refrigerant, itcan be expected to achieve about a 20% reduction in power usagetheoretically, or about a 10% reduction even with an actual apparatus.As a fluid machine that achieves such an attempt, development of a fluidmachine (expander-integrated compressor), such as disclosed in JP2005-299632 A, is underway at a rapid pace.

FIG. 11 is a vertical cross-sectional view illustrating a typicalexpander-integrated compressor. An expander-integrated compressor 200has a two-stage rotary type compression mechanism 121, a motor 122, atwo-stage rotary type expansion mechanism 123, and a closed casing 120that accommodates them. The compression mechanism 121, the motor 122,and the expansion mechanism 123 are coupled to each other by a shaft124.

A bottom part of the closed casing 120 forms an oil reservoir 125 forholding oil (refrigeration oil). An oil pump 126 is fitted to a lowerend portion of the shaft 124 in order to pump up the oil held in the oilreservoir 125. The oil pumped up by the oil pump 126 is supplied to thecompression mechanism 121 and the expansion mechanism 123 via an oilsupply passage 127 formed in the shaft 124. Thereby, lubricity andsealing of the sliding parts of the compression mechanism 121 and theexpansion mechanism 123 are ensured.

An oil return pipe 128 is disposed in an upper part of the expansionmechanism 123. One end of the oil return pipe 128 communicates with theoil supply passage 127 formed in the shaft 124, while the other endopens below the expansion mechanism 123. Generally, the oil is suppliedexcessively in order to ensure the reliability of the expansionmechanism 123. The excess oil is returned via the oil return pipe 128 tothe oil reservoir 125.

By disposing both the compression mechanism 121 and the expansionmechanism 123 in the closed casing 120, there is an advantage in beingable to lubricate both the compression mechanism 121 and the expansionmechanism 123 by the oil held in the oil reservoir 125.

DISCLOSURE OF THE INVENTION

In the expander-integrated compressor 200 shown in FIG. 11, the oilpumped up from the oil reservoir 125 is heated by the compressionmechanism 121 because it passes through the compression mechanism 121that is at a high temperature. The oil heated by the compressionmechanism 121 is heated further by the motor 122, and it reaches theexpansion mechanism 123. The oil having reached the expansion mechanism123 is cooled by the expansion mechanism 123 that is at a lowtemperature, and is thereafter discharged below the expansion mechanism123 via the oil return pipe 128. The oil discharged from the expansionmechanism 123 and the oil return pipe 128 is heated again when passingalong a side face of the motor 122 and is also heated when passing alonga side face of the compression mechanism 121. The oil then returns tothe oil reservoir 125 of the closed casing 120.

As described above, the oil circulation between the compressionmechanism 121 and the expansion mechanism 123 causes heat transfer fromthe compression mechanism 121 to the expansion mechanism 123. Such heattransfer lowers the temperature of the refrigerant discharged from thecompression mechanism 121, and elevates the temperature of therefrigerant discharged from the expansion mechanism 123. In terms of airconditioners, this means a decrease of indoor heating capacity duringheating, or a decrease of indoor cooling capacity during cooling.

It is important to reduce the above-described heat transfer as much aspossible in order to improve cycle efficiency. In particular, when thesystem operates at high output power and the rotation speed of theexpander-integrated compressor is correspondingly high, the amount ofthe oil supplied by the oil pump 126, and accordingly the quantity ofheat transferred by the oil, is great.

The present invention has been accomplished in view of the foregoingcircumstances, and it is an object of the invention to reduce the heattransfer from the compression mechanism to the expansion mechanism.

Accordingly, the present invention provides an expander-integratedcompressor including:

a compression mechanism for compressing a working fluid;

an expansion mechanism for recovering mechanical power from the workingfluid;

a shaft coupling the compression mechanism and the expansion mechanismso as to transmit the mechanical power recovered by the expansionmechanism to the compression mechanism;

a closed casing accommodating the compression mechanism, the expansionmechanism, and the shaft in such a manner that the compression mechanismand the expansion mechanism are arrayed vertically, the closed casinghaving a bottom portion utilized as an oil reservoir and an interiorspace to be filled with the working fluid having been compressed;

an oil pump provided at a lower portion of the shaft; and

an oil supply passage for supplying oil in the oil reservoir to thecompression mechanism or the expansion mechanism located in an upperpart of the closed casing by the oil pump, the oil supply passage beingformed in the shaft so as to extend in an axis direction; and

an oil supply amount regulating mechanism, disposed below thecompression mechanism or the expansion mechanism located in the upperpart of the closed casing, for regulating the amount of the oil to besupplied to the compression mechanism or the expansion mechanism locatedin the upper part of the closed casing through the oil supply passage.

In another aspect, the present invention provides a refrigeration cycleapparatus including:

an expander-integrated compressor according to the present invention;

a radiator for cooling the refrigerant compressed by the compressionmechanism of the expander-integrated compressor; and

an evaporator for evaporating refrigerant expanded by the expansionmechanism of the expander-integrated compressor.

In yet another aspect, the present invention provides anexpander-integrated compressor including:

a compression mechanism for compressing a working fluid;

an expansion mechanism for recovering mechanical power from the workingfluid;

a shaft coupling the compression mechanism and the expansion mechanismso as to transmit the mechanical power recovered by the expansionmechanism to the compression mechanism;

a closed casing accommodating the compression mechanism, the expansionmechanism, and the shaft, the closed casing having a bottom portionutilized as an oil reservoir and an interior space to be filled with theworking fluid having been compressed;

an oil pump provided at an end portion of the shaft;

an oil supply passage for supplying oil in the oil reservoir by the oilpump to the compression mechanism or the expansion mechanism that islocated in a far side, viewed from the oil pump, with respect to an axisdirection of the shaft, the oil supply passage being formed in the shaftso as to extend in the axis direction; and

an oil supply amount regulating mechanism for regulating the amount ofthe oil to be supplied to the compression mechanism or the expansionmechanism through the oil supply passage.

The above-described expander-integrated compressor of the presentinvention is provided with the oil supply amount regulating mechanism.Therefore, an appropriate amount of oil can be supplied to thecompression mechanism or the expansion mechanism regardless of therotation speed of the shaft. As a result, it is possible to reduce theheat transfer from the compression mechanism to the expansion mechanismthat results from the oil circulation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view illustrating anexpander-integrated compressor according to a first embodiment of thepresent invention.

FIG. 2A is a horizontal cross-sectional view taken along line IIA-IIA ofthe expansion mechanism.

FIG. 2B is a horizontal cross-sectional view taken along line IIB-IIB ofan expansion mechanism.

FIG. 3 is a partially enlarged view of FIG. 1.

FIG. 4 is a view illustrating a modified embodiment of an oil supplyamount regulating mechanism.

FIG. 5 is a vertical cross-sectional view illustrating anexpander-integrated compressor according to a second embodiment of thepresent invention.

FIG. 6 is a partially enlarged view of FIG. 5.

FIG. 7 is a vertical cross-sectional view illustrating anexpander-integrated compressor according to a third embodiment of thepresent invention.

FIG. 8 is a partially enlarged view of FIG. 7.

FIG. 9 is a vertical cross-sectional view illustrating anexpander-integrated compressor according to a fourth embodiment of thepresent invention.

FIG. 10 is a configuration diagram of a refrigeration cycle apparatususing the expander-integrated compressor.

FIG. 11 is a vertical cross-sectional view illustrating a conventionalexpander-integrated compressor.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 1 is a vertical cross-sectional view illustrating anexpander-integrated compressor according to a first embodiment of thepresent invention. An expander-integrated compressor 100A has a closedcasing 1, a compression mechanism 2, an expansion mechanism 3, a motor4, a shaft 5, an oil pump 6, and an oil supply amount regulatingmechanism 30. The compression mechanism 2 is disposed in a lower part ofthe closed casing 1. The expansion mechanism 3 is disposed in an upperpart of the closed casing 1. The motor 4 is disposed between thecompression mechanism 2 and the expansion mechanism 3. The compressionmechanism 2, the motor 4, and the expansion mechanism 3 are coupled toeach other by the shaft 5 so that mechanical power can be transmitted.The oil pump 6 is provided at a lower portion of the shaft 5. The oilsupply amount regulating mechanism 30 is for regulating the amount ofthe oil to be supplied to the expansion mechanism 3. In the presentembodiment, a regulating valve (typically a needle valve) is employed asthe oil supply amount regulating mechanism 30.

The motor 4 drives the shaft 5 to operate the compression mechanism 2.The expansion mechanism 3 recovers mechanical power from the expandingworking fluid, and supplies the mechanical power to the shaft 5 toassist the motor 4 to drive the shaft 5. The working fluid is, forexample, a refrigerant such as carbon dioxide and hydrofluorocarbon.

In the present embodiment, the arrangement of the compression mechanism2, the motor 4, and the expansion mechanism 3 is determined in such amanner that the axis direction of the shaft 5 is in agreement with thevertical direction. However, the positional relationship between thecompression mechanism 2 and the expansion mechanism 3 may be opposite ofthat in the present embodiment. In other words, the compressionmechanism 2 may be disposed in an upper part of the closed casing 1, andthe expansion mechanism 3 may be disposed in a lower part of the closedcasing 1.

The closed casing 1 has an interior space 24 for accommodating variouscomponents. The interior space 24 of the closed casing 1 is filled withthe refrigerant compressed by the compression mechanism 2. A bottomportion of the closed casing 1 is utilized as an oil reservoir 25. Theoil is used for ensuring lubrication and sealing on the sliding parts ofthe compression mechanism 2 and the expansion mechanism 3. The amount ofthe oil in the oil reservoir 25 is controlled so that the oil level isbelow the motor 4. This prevents a decrease of the efficiency of themotor and an increase of the oil discharge amount to the refrigerantcircuit, which result from the agitation of the oil by the rotor of themotor 4. Since the temperature of the compression mechanism 2 becomeshigh during operation of the expander-integrated compressor 100A, thetemperature of the oil held in the oil reservoir 25 becomes accordinglyhigh.

The compression mechanism 2 has cylinders 17 and 18, pistons 7 and 8,and bearing members 10 and 11, and it has the same structure as that ofthe conventional two-stage rotary compressor. A suction pipe 13 isconnected to the cylinder 17, and a suction pipe 14 is connected to thecylinder 18. The refrigerant is guided to compression chambers 19 and20, formed in the respective cylinders 17 and 18, through the suctionpipes 13 and 14. The refrigerant compressed in the compression chambers19 and 20 is discharged to the interior space 24 of the closed casing19. A discharge pipe 15 is connected to the closed casing 1 so that anopening thereof is located between the motor 4 and the expansionmechanism 3. The refrigerant discharged to the interior space 24 flowsupward through a region surrounding the motor 4. The refrigerant is thenguided through the discharge pipe 15 to a flow passage outside theclosed casing 1. At that time, the refrigerant and the oil can beseparated from each other by a gravitational force or a centrifugalforce.

In the present embodiment, a rotary-type fluid mechanism is employed asthe compression mechanism 2. The “rotary type” includes not only arolling piston type, in which a vane slides along the outercircumferential surface of a piston, and a sliding vane type, in which avane slides along the inner circumferential surface of a cylinder, butalso a swing piston type, in which a piston and a vane are integrallyformed. In addition, the type of the compression mechanism 2 is notlimited to the rotary type. It is also possible to employ other types offluid mechanisms, such as a scroll type, a reciprocating type, and ascrew type, as the compression mechanism 2. The same applies to thelater-described expansion mechanism 3.

The motor 4 has a stator 21 fixed to the closed casing 1 and a rotor 22fixed to the shaft 5. Electric power is supplied to the motor 4 througha terminal (not shown) disposed at the top of the closed casing 1.

An oil supply passage 29 communicating with sliding parts of theexpansion mechanism 3 is formed in the shaft 5 so as to extend in theaxis direction. This is desirable because, when forming the oil supplypassage 29 inside the shaft 5, the problems associated with an increasein the parts count and parts layout do not arise. The oil is supplied tosliding parts of the expansion mechanism 3 through the oil supplypassage 29.

In the present embodiment, the oil supply passage 29 does not open inthe upper end face of the shaft 5. In this way, the oil does not flowout over the expansion mechanism 3, unlike the conventional exampledescribed with reference to FIG. 11. Thereby, the oil is less easilycooled by the expansion mechanism 3. In other words, the heat transferfrom the compression mechanism 2 to the expansion mechanism 3 can bereduced more effectively. However, the oil supply passage 29 may open inthe upper end face of the shaft 5.

The shaft 5 may be made of a single component, or may be made bycombining (coupling) a plurality of components together. Specifically,the shaft 5 may include a first shaft on the compression mechanism 2side and a second shaft on the expansion mechanism 3 side. The firstshaft and the second shaft may be coupled directly by fitting them ontoeach other, or may be coupled to each other via another component(coupler). When the shaft 5 is made of a combination of a plurality ofcomponents, assembling, especially alignment between the compressionmechanism 2 and the expansion mechanism 3, becomes easy.

The expansion mechanism 3 has a first cylinder 42, a second cylinder 44having an inner diameter larger than the inner diameter of the firstcylinder 42, an intermediate plate 43 partitioning the first cylinder 42and the second cylinder 44. The first cylinder 42 and the secondcylinder 44 are disposed concentrically with each other. As illustratedin FIGS. 2A and 2B, the expansion mechanism 3 further has a first piston46, a first vane 48, a first spring 50, a second piston 47, a secondvane 49, and a second spring 51.

As illustrated in FIG. 2A, the first piston 46 is fitted with aneccentric portion 5 c of the shaft 5, and it performs eccentricrotational motion in the first cylinder 42. The first vane 48 isretained reciprocably in a vane groove 42 a formed in the first cylinder42. One end of the first vane 48 is in contact with the first piston 46.The first spring 50 is in contact with the other end of the first vane48, and biases the first vane 48 toward the first piston 46.

As illustrated in FIG. 2B, the second piston 47 is fitted with aneccentric portion 5 d of the shaft 5, and it performs eccentricrotational motion in the second cylinder 44. The second vane 49 isretained reciprocably in a vane groove 44 a formed in the secondcylinder 44. One end of the second vane 49 is in contact with the secondpiston 47. The second spring 51 is in contact with the other end of thesecond vane 49, and biases the second vane 49 toward the second piston47.

The expansion mechanism 3 further has a bearing member 45 and a bearingmember 41. The bearing member 41 is fitted to the closed casing 1 withno clearance between them. The components such as the cylinders and theintermediate plate are fixed to the closed casing 1 via the bearingmember 41. The bearing member 41 and the intermediate plate 43sandwiches the first cylinder 42 from the top and bottom, and theintermediate plate 43 and the bearing member 45 sandwiches the secondcylinder 44 from the top and bottom. Sandwiching the bearing member 45,the intermediate plate 43, and the bearing member 41 forms workingchambers 55 and 56 in the first cylinder 42 and the second cylinder 44,respectively.

As illustrated in FIG. 2A, a suction-side working chamber 55 a (firstsuction-side space) and a discharge-side working chamber 55 b (firstdischarge-side space) are formed inside the first cylinder 42. Theworking chamber 55 a and the working chamber 55 b are partitioned by thefirst piston 46 and the first vane 48. As illustrated in FIG. 2B, asuction-side working chamber 56 a (second suction-side space) and adischarge-side working chamber 56 b (second discharge-side space) areformed inside the second cylinder 44. The working chamber 56 a and theworking chamber 56 b are partitioned by the second piston 47 and thesecond vane 49. The total volumetric capacity of the two workingchambers 56 a and 56 b in the second cylinder 44 is greater than thetotal volumetric capacity of the two working chambers 55 a and 55 b inthe first cylinder 42. The discharge-side working chamber 55 b of thefirst cylinder 42 and the suction-side working chamber 56 a of thesecond cylinder 44 are brought into communication with each otherthrough a through hole 43 a formed in the intermediate plate 43, so thatthey can function as a single working chamber (an expansion chamber).

The method for making the total volumetric capacity of the workingchambers 56 a and 56 b greater than the total volumetric capacity of theworking chambers 55 a and 55 b is not limited to the method of varyingthe inner diameters of the first cylinder 42 and the second cylinder 44.It is also possible to employ the method of appropriately setting thethicknesses of the cylinders 42 and 44 or the outer diameters of thepistons 46 and 47.

The expansion mechanism 3 further has a suction pipe 52 serving as asuction passage for directly drawing the refrigerant that has not yetbeen expanded from a flow passage external to the closed casing 1, and adischarge pipe 53 serving as a discharge passage for directlydischarging the refrigerant that has been expanded to a flow passageexternal to the closed casing 1. Specifically, the suction pipe 52 isdirectly inserted in the first cylinder 42 so that the refrigerant canbe guided from the flow passage external to the closed casing 1 to theworking chamber 55 of the first cylinder 42. The discharge pipe 53 isdirectly inserted in the second cylinder 44 so that the refrigerant canbe guided from the working chamber 56 of the second cylinder 44 to theflow passage external to the closed casing 1. The suction pipe 52 may beinserted in the bearing member 41, and the discharge pipe 53 may beinserted in the bearing member 45.

The refrigerant that has not yet been expanded passes through thesuction pipe 52 and flows into the working chamber 55 a of the firstcylinder 42. The working fluid having flowed into the working chamber 55a of the first cylinder 42 moves to the working chamber 55 b inassociation with rotation of the shaft 5, and it expands and reduces itspressure in the expansion chamber formed by the working chamber 55 b,the through hole 43 a, and the working chamber 56 a, while rotating theshaft 5. The refrigerant having expanded is guided to the outside of theclosed casing 1 through the working chamber 56 b and the discharge pipe53.

The location at which the oil pump 6 is provided is a lower portion ofthe shaft 5. Specifically, the oil pump 6 is disposed in the oil supplypassage 29 in a lower portion of the shaft 5. Disposing the oil pump 6in the oil supply passage 29 eliminates the need to provide an oilsupply pipe separately.

The oil pump 6 is operated by the mechanical power supplied from theshaft 5. In the present embodiment, a velocity type pump (turbine pump)is employed as the oil pump 6. Specifically, the oil pump 6 has a pumpblade 6 a and a blade stopper 6 b. The pump blade 6 a is fixed to theshaft 5 by the blade stopper 6 b. Rotation of the pump blade 6 atogether with the shaft 5 causes the oil to be pumped upward. Generally,the rotation speed of the oil pump 6 is equal to the rotation speed ofthe shaft 5. Therefore, as the rotation speed of the shaft 5 increases,the delivery capacity and delivery pressure of the oil pump 6 increasesaccordingly. However, since the effectiveness of the oil supply amountregulating mechanism 30 increases as the delivery pressure of the oilpump 6 increases, the amount of the oil to be supplied to the expansionmechanism 3 is not proportional to the rotation speed of the shaft 5.

The type of the oil pump is not limited to the velocity type pump, and apositive displacement pump may be used. Examples of the positivedisplacement pump include a rotary type oil pump and a TROCHOID pump(registered trademark of Nippon Oil Pump Co., Ltd.). However, thevelocity type pump is better suited for the oil supply amount regulatingmechanism 30 in the present embodiment than the positive displacementpump. The reason is that no oil escape route is provided in the presentembodiment, as it is provided in the later-described second and thirdembodiments.

The oil supply amount regulating mechanism 30 includes a structure forpreventing the amount of the oil to be supplied to the expansionmechanism 3 through the oil supply passage 29 from increasingcorrespondingly to an increase of the rotation speed of the shaft 5. Asdescribed previously, it is important to reduce the heat transfer fromthe compression mechanism 2 to the expansion mechanism 3 resulting fromthe oil circulation as much as possible, in order to improve theefficiency of a refrigeration cycle apparatus (see FIG. 10) using theexpander-integrated compressor 100A. When the rotation speed of theshaft 5 increases, the delivery capacity and delivery pressure of theoil pump 6 tend to increase. However, excessive supply of the oil isprevented by the workings of the oil supply amount regulating mechanism30. In some cases, the oil supply amount to the expansion mechanism 3can be maintained at almost a constant level regardless of the rotationspeed of the shaft 5. As a result, it is possible to reduce the heattransfer from the compression mechanism 2 to the expansion mechanism 3that results from the oil circulation.

In the present embodiment, the oil supply amount regulating mechanism 30is provided in the oil supply passage 29. For this reason, it isunnecessary to provide a dedicated space for the oil supply amountregulating mechanism 30. The location at which the oil supply amountregulating mechanism 30 should be provided may be below the expansionmechanism 3, which is located in the upper part of the closed casing 1.Typically, the oil supply amount regulating mechanism 30 is providedbetween the working chamber 20 of the compression mechanism 2 and themotor 4 with respect to the axis direction of the shaft 5.

FIG. 3 is a partially enlarged view of FIG. 1. As illustrated in FIG. 3,the oil supply amount regulating mechanism 30 has a valve seat 31, aneedle 32 (valve body), a spring 33, and a needle stopper 34. The valveseat 31 has an orifice shape whose inner diameter decreases toward theexpansion mechanism 3. The needle 32 is disposed so as to face the valveseat 31. The needle 32 has a leading end portion in a circular conicshape. The spring 33 is disposed between the valve seat 31 and theneedle 32 so that a gap through which the oil can flow is formed betweenthe valve seat 31 and the needle 32. The spring 33 expands and contractsaccording to a pressure change of the oil in the oil supply passage 29,so that the gap between the valve seat 31 and the needle 32 can beadjusted. The needle stopper 34 for defining the range of motion of theneedle 32 is disposed opposite the valve seat 31 across the needle 32.The valve seat 31 or the needle stopper 34 may be formed by a portion ofthe shaft 5.

With the oil supply amount regulating mechanism 30, the oil to besupplied to the expansion mechanism 3 flows through the oil supplypassage 29 and hits the back face of the needle 32. Thereafter, the oilpasses through the surrounding region of the needle 32 and flows towardthe valve seat 31. The oil hitting the back face of the needle 32presses the needle 32 toward the valve seat 31 with a forcecorresponding to the flow rate of the oil. The needle 32 is pushed backwith a force in proportion to the displacement of the spring 33.Specifically, the area of the gap between the valve seat 31 and theneedle 32 (the cross-sectional area of the gap) changes according to theflow rate of the oil. While the oil feeding capability of the oil pump 6becomes higher in proportional to an increase of the rotation speed ofthe shaft 5, the resistance to the oil flow increases because the gapbetween the valve seat 31 and the needle 32 narrows. As a result, theamount of the oil to be supplied is restricted (optimized).

Even when the shaft 5 revolves at a high speed, an unnecessarily greatamount of the oil is not supplied to the expansion mechanism 3 becauseof the workings of the oil supply amount regulating mechanism 30. Inother words, an appropriate amount of the oil can be supplied to theexpansion mechanism 3. As a result, it is possible to reduce the heattransfer from the compression mechanism 2 to the expansion mechanism 3that results from the oil circulation. Moreover, since excess oil is notsupplied to the expansion mechanism 3, it is possible to prevent theworking fluid from mixing with a large amount of the oil in theexpansion mechanism 3. Thus, it is possible to prevent a considerabledecrease in heat exchange efficiency resulting from the excess oilflowing into an evaporator 102 (see FIG. 10). As illustrated in FIG. 4,the effect of optimizing the oil supply amount can be obtained byproviding only the valve seat 31 in the oil supply passage 29. That is,by merely providing an orifice in the oil supply passage 29, the oil canbe prevented from being excessively supplied to the expansion mechanism3 because the pressure loss at the orifice increases proportionally toan increase of the oil flow rate.

In the present embodiment, the oil of the oil supply passage 29 issupplied only to the expansion mechanism 3. However, the oil of the oilsupply passage 29 may also be supplied to the compression mechanism 2.

Second Embodiment

FIG. 5 is a vertical cross-sectional view illustrating anexpander-integrated compressor according to a second embodiment of thepresent invention. As illustrated in FIG. 5, a main difference betweenan expander-integrated compressor 100B of the present embodiment and theexpander-integrated compressor 100A of the first embodiment is in theoil supply amount regulating mechanism. The same parts as those in theembodiment shown in FIG. 1 will be designated by the same referencenumerals, and the descriptions thereof will be omitted.

FIG. 6 is a partially enlarged view of FIG. 5. In the presentembodiment, a branch passage 29 s branching in a radial direction fromthe oil supply passage 29 and opening in an outer circumferentialsurface of the shaft 5 is formed in the shaft 5. An oil supply amountregulating mechanism 60 is provided in the branch passage 29 s. In thisway, mounting of the oil supply amount regulating mechanism 60 ispossible from the outside of the shaft 5, so assembling is easier thanthat in the first embodiment. Moreover, this is suitable also in thecase where the oil pump is a positive displacement pump because thebranch passage 29 s behaves as an oil escape route.

As illustrated in FIG. 6, the oil supply amount regulating mechanism 60has a valve seat 61, a needle 62, a spring 63, and a needle stopper 64.The valve seat 61 has an orifice shape whose inner diameter decreasestoward the oil supply passage 29. The valve seat 61 is disposed at aportion of the branch passage 29 s that faces the oil supply passage 29.The needle 62 in a circular conic shape is disposed so as to face thevalve seat 61. The needle 62 is displaceable in a direction toward thevalve seat 61 and a direction away from the valve seat 61 (radialdirections of the shaft 5). The needle stopper 64 is disposed at aportion of the branch passage 29 s that faces an outside of the shaft 5.The needle stopper 64 defines the range of motion of the needle 62. Thespring 63 is disposed between the needle 62 and the needle stopper 64.

A bearing member 10 has a bearing portion 10 a that supports the shaft5. The bearing portion 10 a covers an outer circumferential surface ofthe shaft 5 at a location where the branch passage 29 s is formed. Acircular chamber 67 is formed in an inner circumferential surface of thebearing portion 10 a. The branch passage 29 s opens toward the chamber67. An oil discharge passage 66 for connecting the chamber 67 and theinterior space 24 of the closed casing 1 is further formed in thebearing portion 10 a so as to penetrate through the bearing portion 10 ain a radial direction. By the branch passage 29 s, the chamber 67, andthe oil discharge passage 66, the oil can flow from the oil supplypassage 29 to the interior space 24 of the closed casing 1.

When the internal pressure of the oil supply passage 29 is lower than apredetermined pressure, the oil supply amount regulating mechanism 60 isbrought to a closed state. The closed state refers to a state in whichthe branch passage 29 s is closed by the needle 62 being fitted into thevalve seat 61. In the closed state, the oil cannot flow through thebranch passage 29 s. On the other hand, when the rotation speed of theshaft 5 increases and the internal pressure of the oil supply passage 29thereby becomes higher than a predetermined pressure, the oil supplyamount regulating mechanism 60 is brought to an open state. The openstate refers to a state in which the needle 62 is detached from thevalve seat 61 so that a gap is formed between the valve seat 61 and theneedle 62. In the open state, the oil can flow through the branchpassage 29 s.

When the internal pressure of the oil supply passage 29 becomes higherthan the predetermined pressure, the oil enters the branch passage 29 sthrough the valve seat 61 while displacing the needle 62. The force ofthe oil that displaces the needle 62 is proportional to the internalpressure of the oil supply passage 29. On the condition that the outwardload that is applied to the needle 62 by the oil in the oil supplypassage 29 and the like (more specifically, the pressure of the oil andthe centrifugal force) exceeds the force by which the spring 63 pushesthe needle 62 when the oil supply amount regulating mechanism 60 is inthe closed state, the oil supply amount regulating mechanism 60 switchesfrom the closed state to the open state.

In other words, when the rotation speed of the shaft 5 increases and theoil is fed into the oil supply passage 29 in an amount greater than isnecessary, the increase of the internal pressure of the oil supplypassage 29 brings the oil supply amount regulating mechanism 60 into theopen state. When the oil supply amount regulating mechanism 60 isbrought into the open state, part of the oil flowing through the oilsupply passage 29 is guided to the outside of the shaft 5 through thebranch passage 29 s. The oil having flowed out of the shaft 5 isdischarged to the interior space 24 of the closed casing 1 through thechamber 67 and the oil discharge passage 66 formed in the bearingportion 10 a of the bearing member 10. As a result, the amount of theoil to be supplied to the expansion mechanism 3 is optimized. Thus, inthe present embodiment, the oil supply amount regulating mechanism 60 isconstructed by a relief valve.

In addition, in the present embodiment, the oil is allowed to escape tothe outside of the shaft 5 through the branch passage 29 s. For thisreason, when the oil supply amount regulating mechanism 60 is broughtinto the open state, a difference in the flow rate of the oil in the oilsupply passage 29 arises between the positions before and after the oilsupply amount regulating mechanism 60. Specifically, the flow rate ishigh between the oil supply amount regulating mechanism 60 and the oilpump 6, and the flow rate is low between the expansion mechanism 3 andthe oil supply amount regulating mechanism 60. It is preferable that theportion at which the flow rate of the oil is high be farther away fromthe expansion mechanism 3, from the view point of reducing the heattransfer from the compression mechanism 2 to the expansion mechanism 3that results from the oil circulation. Therefore, it is desirable thatthe branch passage 29 s be formed in a portion of the shaft 5 that isbetween the motor 4 and the compression mechanism 2.

Third Embodiment

FIG. 7 is a vertical cross-sectional view illustrating anexpander-integrated compressor according to a third embodiment of thepresent invention. As illustrated in FIG. 7, a main difference betweenan expander-integrated compressor 100C of the present embodiment and theexpander-integrated compressor 100A of the first embodiment is in theoil supply amount regulating mechanism.

FIG. 8 is a partially enlarged view of FIG. 7. In the presentembodiment, a branch passage 29 t branching in a radial direction fromthe oil supply passage 29 and opening in an outer circumferentialsurface of the shaft 5 is formed in the shaft 5. An oil supply amountregulating mechanism 70 is provided exteriorly of the shaft so that theoil is guided to the interior space 24 of the closed casing 1 throughthe branch passage 29 t. Since the oil supply amount regulatingmechanism 70 is provided exteriorly of the shaft 5, a larger space thanis available in the preceding two embodiments can be ensured for the oilsupply amount regulating mechanism 70.

The present embodiment is similar to the second embodiment in therespect that the branch passage 29 t is formed in the shaft 5 as an oilescape route. On the other hand, the present embodiment is differentfrom the second embodiment in the respect that the oil supply amountregulating mechanism 70 does not rotate together with the shaft 5. Thisis suitable also in the case where the oil pump is a positivedisplacement pump because the branch passage 29 t behaves as an oilescape route.

As illustrated in FIG. 8, in the present embodiment, the oil supplyamount regulating mechanism 70 is provided inside the bearing member 10.The bearing member 10 has the bearing portion 10 a that supports theshaft 5. The bearing portion 10 a covers an outer circumferentialsurface of the shaft 5 at a location where the branch passage 29 t isformed. A circular chamber 77 is formed in an inner circumferentialsurface of the bearing portion 10 a. The branch passage 29 t openstoward the chamber 77. An oil discharge passage 76 is further formed inthe bearing portion 10 a, as a passage for connecting the chamber 77 andthe interior space 24 of the closed casing 1. The oil supply amountregulating mechanism 70 is provided in the oil discharge passage 76.

The oil supply amount regulating mechanism 70 has a valve seat 71, avalve body 72, a spring 73, and a valve body stopper 74. The oildischarge passage 76 includes a portion having a T-shapedcross-sectional shape along the flow direction of the oil. The valveseat 71 is disposed in the T-shaped portion. The valve body 72 in aspherical shape is disposed so as to face the valve seat 71. The valvebody stopper 74 is disposed opposite the valve seat 71 across the valvebody 72. The valve body stopper 74 defines the range of motion of thevalve body 72. The spring 73 is disposed between the valve body 72 andthe valve body stopper 74. It should be noted that the structure of theoil supply amount regulating mechanism 70 may be the same as that in thesecond embodiment.

When the internal pressure of the oil supply passage 29 is lower than apredetermined pressure, the oil supply amount regulating mechanism 70 isbrought to a closed state. The closed state refers to a state in whichthe oil discharge passage 76 is closed by the valve body 72 being fittedinto the valve seat 71. In the closed state, the oil cannot flow throughthe oil discharge passage 76. On the other hand, when the rotation speedof the shaft 5 increases and the internal pressure of the oil supplypassage 29 thereby becomes higher than the predetermined pressure, theoil supply amount regulating mechanism 70 is brought to an open state.The open state refers to a state in which the valve body 72 is detachedfrom the valve seat 71 so that a gap is formed between the valve seat 71and the valve body 72. In the open state, the oil can flow through theoil discharge passage 76.

When the internal pressure of the oil supply passage 29 becomes higherthan the predetermined pressure, the oil displaces the valve body 72,causing the oil discharge passage 76 to open. The force of the oil thatdisplaces the valve body 72 is proportional to the internal pressure ofthe oil supply passage 29. On the condition that the load that isapplied to the valve body 72 by the oil in the oil supply passage 29exceeds the force by which the spring 73 pushes the needle 72 when theoil supply amount regulating mechanism 70 is in the closed state, theoil supply amount regulating mechanism 70 switches from the closed stateto the open state.

In other words, when the rotation speed of the shaft 5 increases and theoil is fed into the oil supply passage 29 in an amount greater than isnecessary, the increase of the internal pressure of the oil supplypassage 29 brings the oil supply amount regulating mechanism 70 into theopen state. When the oil supply amount regulating mechanism 70 isbrought into the open state, part of the oil flowing through the oilsupply passage 29 is guided to the outside of the shaft 5 through thebranch passage 29 t. The oil having flowed out of the shaft 5 isdischarged to the interior space 24 of the closed casing 1 through thechamber 77 and the oil discharge passage 76 each formed in the bearingportion 10 a of the bearing member 10. As a result, the amount of theoil to be supplied to the expansion mechanism 3 is optimized. Thus, inthe present embodiment as well, the oil supply amount regulatingmechanism 70 is constructed by a relief valve.

It should be noted that the oil supply amount regulating mechanism 70may be disposed at an outlet of the oil discharge passage 76, or may bedisposed in the chamber 77.

In the present embodiment as well, the oil is allowed to escape to theoutside of the shaft 5 through the branch passage 29 t. Therefore, it isdesirable that the branch passage 29 t be formed in a portion of theshaft 5 that is between the motor 4 and the compression mechanism 2,which is located in the lower part of the closed casing 1.

Fourth Embodiment

In an expander-integrated compressor 100D of the present embodiment, theaxis direction of the shaft 5 is parallel to the horizontal direction,as illustrated in FIG. 9. The oil reservoir 25 is formed along thelongitudinal direction of the closed casing 1. A partition wall 27 isprovided between the expansion mechanism 3 and the motor 4. Thepartition wall 27 divides the interior space 24 into a space on theexpansion mechanism 3 side and a space on the compression mechanism 2side. The motor 4 is disposed also in the space on the compressionmechanism 2 side. This partition wall 27 also has the function to reducethe heat transfer from the compression mechanism 2 and the motor 4 tothe expansion mechanism 3. The partition wall 27 has a passage 27 hallowing the oil to flow therethrough.

A positive displacement-type the oil pump 26 is provided at an endportion of the shaft 5. The oil pump 26, the expansion mechanism 3, themotor 4, and the compression mechanism 2 are arrayed in that order alongthe axis direction of the shaft 5. The oil supply amount regulatingmechanism 60 is the same one as described with reference to FIG. 6 inthe third embodiment. A nozzle 26 k of the oil pump 26 extends towardthe oil reservoir 25 so that it can draw the oil in the oil reservoir25. The oil drawn by the oil pump 26 is supplied through the oil supplypassage 29 to the compression mechanism 2 located in the far side,viewed from the oil pump 26, with respect to the axis direction theshaft 5. In the present embodiment, the oil from the oil pump 26 is alsosupplied to the expansion mechanism 3, which is located on the nearside, viewed from the oil pump 26. The oil discharged from the oilsupply passage 29 through the oil supply amount regulating mechanism 60returns to the space on the expansion mechanism 3 side.

As in the foregoing embodiments, the oil supply amount regulatingmechanism 60 prevents excessive supply of the oil. Thereby, the heattransfer from the compression mechanism 2 to the expansion mechanism 3is suppressed. In the embodiment shown in FIG. 9, the oil pump 26 isprovided in the expansion mechanism 3 side. However, it is possible toprovide the oil pump 26 in the compression mechanism 2 side. It is alsopossible to provide the oil supply amount regulating mechanism 30 (firstembodiment) or the oil supply amount regulating mechanism 70 (thirdembodiment), in place of the oil supply amount regulating mechanism 60.

INDUSTRIAL APPLICABILITY

The expander-integrated compressor according to the present inventionmay be suitably applied to, for example, refrigeration cycle apparatuses(heat pumps) for air conditioners, water heaters, driers, orrefrigerator-freezers. As illustrated in FIG. 10, a refrigeration cycleapparatus 110 includes: an expander-integrated compressor 100A (, 100B,100C, or 100D); a radiator 101 for cooling the refrigerant compressed bythe compression mechanism 2; and an evaporator 114 for evaporating therefrigerant expanded by the expansion mechanism 3. The compressionmechanism 2, the radiator 101, the expansion mechanism 3, and theevaporator 102 are connected by pipes, to form a refrigerant circuit.

For example, when refrigeration cycle apparatus 110 is applied to an airconditioner, it is possible to prevent a decrease in heating capacitycaused by a decreased discharge temperature of the compression mechanism2 during heating operation, and a decrease in cooling capacity caused byan increased discharge temperature of the expansion mechanism 3 duringcooling operation, by reducing the heat transfer from the compressionmechanism 2 to the expansion mechanism 3. As a result, the coefficientof performance of the air conditioner is improved.

1. An expander-integrated compressor comprising: a rotary-typecompression mechanism for compressing a working fluid; a rotary-typeexpansion mechanism for recovering mechanical power from the workingfluid; a shaft coupling the rotary-type compression mechanism and therotary-type expansion mechanism so as to transmit the mechanical powerrecovered by the rotary-type expansion mechanism to the rotary-typecompression mechanism; a closed casing accommodating the rotary-typecompression mechanism, the rotary-type expansion mechanism, and theshaft in such a manner that the rotary-type compression mechanism andthe rotary-type expansion mechanism are arrayed vertically, the closedcasing having a bottom portion utilized as an oil reservoir and aninterior space to be filled with the working fluid having beencompressed; an oil pump provided at a lower portion of the shaft; an oilsupply passage for supplying oil in the oil reservoir to the rotary-typecompression mechanism or the rotary-type expansion mechanism located inan upper part of the closed casing by the oil pump, the oil supplypassage being formed in the shaft so as to extend in an axis direction;and an oil supply amount regulating mechanism, disposed below therotary-type compression mechanism or the rotary-type expansion mechanismlocated in the upper part of the closed casing and disposed above therotary-type compression mechanism or the rotary-type expansion mechanismlocated in a lower part of the closed casing, for regulating the amountof the oil to be supplied through the oil supply passage to therotary-type compression mechanism or the rotary-type expansion mechanismlocated in the upper part of the closed casing, and wherein: a branchpassage is formed in the shaft, the branch passage branching in a radialdirection from the oil supply passage and opening in an outercircumferential surface of the shaft; and the oil supply amountregulating mechanism is provided in the branch passage or exteriorly ofthe shaft so that the oil is guided to the interior space of the closedcasing through the branch passage.
 2. The expander-integrated compressoraccording to claim 1, wherein the oil supplied through the oil supplypassage does not flow out over the rotary-type compression mechanism orthe rotary-type expansion mechanism located in the upper part of theclosed casing.
 3. The expander-integrated compressor according to claim1, wherein the oil supply passage does not open in an upper end face ofthe shaft.
 4. The expander-integrated compressor according to claim 1,wherein the oil supply amount regulating mechanism includes a structurefor preventing the amount of the oil to be supplied to the rotary-typecompression mechanism or the rotary-type expansion mechanism through theoil supply passage, from increasing correspondingly to an increase of arotation speed of the shaft.
 5. The expander-integrated compressoraccording to claim 1, wherein the oil supply amount regulating mechanismincludes an orifice, a needle valve, or a relief valve.
 6. Theexpander-integrated compressor according to claim 1, further comprising:a motor, disposed between the rotary-type compression mechanism and therotary-type expansion mechanism, for driving the shaft; and wherein thebranch passage is formed in a portion of the shaft that is between themotor and the rotary-type compression mechanism or the rotary-typeexpansion mechanism located in the lower part of the closed casing. 7.The expander-integrated compressor according to claim 1, wherein: therotary-type compression mechanism or the rotary-type expansion mechanismincludes a bearing portion for supporting the shaft and covering theouter circumferential surface of the shaft at a location where thebranch passage is formed; (i) a chamber in which the branch passageopens and (ii) an oil discharge passage for connecting the chamber andthe interior space of the closed casing are formed in the bearingportion; and the oil is guided from the oil supply passage to theinterior space of the closed casing through the branch passage, thechamber, and the oil discharge passage.
 8. The expander-integratedcompressor according to claim 1, wherein the oil supply amountregulating mechanism includes a valve seat, a valve body disposed so asto face the valve seat, and a spring for adjusting a gap between thevalve seat and the valve body by expanding and contracting according toa pressure change of the oil in the oil supply passage.
 9. Theexpander-integrated compressor according to claim 8, wherein the shapeof the valve body is spherical.
 10. The expander-integrated compressoraccording to claim 7, wherein the oil supply amount regulating mechanismis provided in the chamber, in the oil discharge passage, or at anoutlet of the oil discharge passage.
 11. The expander-integratedcompressor according to claim 1, wherein the oil pump is a velocity typepump.
 12. A refrigeration cycle apparatus comprising: anexpander-integrated compressor according to claim 1; a radiator forcooling the refrigerant compressed by the rotary-type compressionmechanism of the expander-integrated compressor; and an evaporator forevaporating the refrigerant expanded by the rotary-type expansionmechanism of the expander-integrated compressor.
 13. (canceled)